Two way lever type telephone key



June 28, 1960 J. L. DUBEAU 2,943,158

TWO WAY LEVER TYPE TELEPHONE KEY Filed May 22, 1958 5 Sheets-Sheet 1 1#7 Due/15 -JEAN L. DUBEAU J 1 J. L. DUBEAU 2,943,158

TWO WAY LEVER TYPE TELEPHONE KEY Filed May 22. 1958 3 Sheets-Sheet 2171067615 47 JEAN LDUBEAU mad 4. M

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June 28, 1960 J. 1... DUBEAU 2,943,153

TWO WAY LEVER TYPE TELEPHONE KEY Filed May 22, 1958 3 Sheets-Sheet 3 Yflue/2%? J54 1.2118540 United States Patent 2,943,158 'rwo WAY LEVERTYPE TELEPHONE KEY Jean L. Dubeau, Montreal, Quebec, Canada, assignor toNorthern Electric Company, Limited, Montreal, Quebe'c, Canada, acorporation of Canada Filed May 22, 1958, Ser. No. 737,050

3 Claims. (Cl. 200-1) This invention relates to switching keys and moreparticularly to two-way lever type keys employed in telephone equipment.

Keys of the nature to which this invention relates generally consist ofa pivoted lever carrying actuating rollers of insulating material, forselectively operating sets of contact springs arranged on both sides ofthe lever. The operation of the springs is effected by actuating thelever to one side or the other for the purpose of rotating the rollersinto the operative position of the respective contact springs. Keys ofthis structure suffer from the eifect of the rebound action, incident tothe return of the key lever to its normal position, which producedmomentary actuation of the non-operated spring assembly with aconsequent disturbance of the circuit controlled by the latter springassembly. In order to remedy this defect, it is customary to providespecially shaped springs, generally known in the art as shepherds crooksprings, which act as a buffer or brake against the returning keyassembly.

The main object of this invention is to provide an improved two-waytelephone key having improved means for preventing the undesireddisturbance of the nonoperated circuit elements when the key leverassembly is returned to its normal position.

A further object of this invention is to provide an improved two-waytelephone key, having improved means for preventing the undesireddisturbance of the non-operated circuit elements when the key leverassembly is returned to its normal position, which isbconomical toconstruct.

These and other objects of this invention are attained by providing atwo-way operated key which includes in combination: a pivotally mountedlever member with spring contact assemblies disposed on both sides of acam pivotally mounted on the lever, arranged for coaction with thesprings, the lever and cam being pivoted in relation to each other andthe cam being so shaped that the force transmitted to the spring contactassemblies by the cam, upon its return to its normal position, isreduced with respect to switching keys provided in the past.

A better understanding of the invention may be obtained by referring tothe following description, taken in conjunction with the drawings, inwhich like numerals refer to like parts, in which:

Fig. 1 is an enlarged side elevation of a two-way locking or non-lockingswitching key, employing the invention, in the normal non-operatedposition;

Fig. 2 is a section taken at 2--2 of Fig. 1 in the direction of thearrows;

Figs. 3, 4, 5 and 6 are enlarged partial side elevations of thepositions which the elements of the switch, employing the invention,assume as the cam is actuated from its normal position in the directionshown; and

Fig. 7 shows one greatly enlarged cam, used in the invention, employedin explaining the invention.

Referring now in detail to the drawings, the key com- Patented June 28,1960 prises a key frame 1, partially shown; lever 2,having handle 3 andprojections 4, 5, projection 4 extending a predetermined distanceupwards with respect to the projection so that .the key is in thelocking and non-locking position when the handle 3 is actuated clockwiseand counterclockwise respectively, pivoted on frame 1 by pin 6; a cam 7made of electrical insulating material such asnylon, pivoted on lever 2by the pin 8, having principal pairs of edge faces 9, 10 and 11, 12, theindividual faces of each pair being disposed at an angle to form thecontact points 13 and 14' respectively, edge faces 9, 10 and 11, 12being slightly curved; a set of spring contact assemblies, generallyshown as 15, 16, each comprising normal springs 17, 18, given a slighttension and having their free ends 19, 20 formed at 21, 22 respectively,ata predetermined angle with respect to the center line of.

the springs 17, 18, contact springs 23, 24, for making contact withnormal springs 17 and 18, the spring contact assemblies being separatedby insulator 25. Cam 7 may be formed with other suitable configurations.

In the normal unoperated position as shown in Fig. 1, the free ends 19,20 of the springs 17, 18 rest on the points 13, 14 of the sides 9, 10and 11, 12 respectively.

Assume now that the handle 3 is moved from the left to I On furthermovement of .the handle 3 from left to right, the free end 19 of spring17 remains tangent to the arc of the face 9 of the cam 7, the centerpoint 19 pressing against the free end 19 of spring 17 thus actuatingthe normal spring 17 and the associated contact spring 23 into theirmake position, as shown in Fig. 5.

On still further movement of the handle 3, face 9 of cam 7 slides on thefree end 19 of spring 17 on the tangent point 19' until the travel ofcam 7 is arrested by the projection 5. striking against the under sideof the frame 1 as in Fig. 6. The key'n'ow locks in this operatedposition due to the imaginary line through the pins 6 and 8 cutting freeend 19 at a point more than halfway from spring 17.

When the handle 3 is released so that the switch is returned to itsnormal unoperated position, Fig. 1, due to the surface frictionalsliding action of the free end 19 of spring 17 on the cam 7, the actionbeing the reverse of when the handle 3 was moved from left to right asdescribed heretofore, the return of the cam 7 is delayed so that theforce with which the cam 7 strikes the free end 20 of spring 18 isreduced, thus diminishing the disturbance to the circuit elementsassociated with spring 18. The friction must be only sufiicient topermit the sliding action between the free end 19 of spring 17 and thecam 7.

,By disposing the projection 4 above projection 5, i.e. closer to theunderside of frame 1, the distance that the cam 7 travels when thehandle 3 is moved from right to left is decreased, thereby making theswitch non-locking in this position.

What is claimed is:

l. A telephone switching key comprising in combination: a support; aplate-like lever pivotally mounted on the support; a plate-likerotatable cam of insulating material, pivotally mounted at its upper endon the lever, having two opposite edge faces arranged at an angle witheach other; spring contact assemblies individually disposed adjacent=the edges faces, each assembly including a main spring inwardlydeflected and outwardly otfset at its free end, with respect to thelongitudinal center line of the cam, to form a point of contact with anedge face of the cam, the friction between the said edge face and thefree end of the main spring being only suf ficient-to permit the slidingof such elements with respect 5 to each other when the key is operated.

2. A telephone switching key comprising in combination: a support; aplate-like lever pivotally mounted on the support; a cam of insulatingmaterial, pivotally mounted at its upper end on the lever, having two ofits 10 opposite edge faces arranged at an angle with each other; springcontact assemblies individually disposed adjacent the edge faces, eachassembly including a main spring inwardly deflected and outwardly offsetat its free end, with respect to the longitudinal center line of thecam, to 1 4 form a point of contact with an edge face of the cam; thefriction between the said edge .-faceand the. free end of the mainspring being only sufiicient to permit the sliding of such elementswithrespect to each other when the key is operated.

3. A telephone switching key in accordance with claim 1 in which thesaid lever is provided with ears integral therewith, disposed at itsouter extremity and arranged to limit the travel "of the lever when itis operated;

References Cited in the file of this patent UNITED STATES PATENTSMacDonald Mar. 23, 1954 Barber Dec. 13, 1955

